Hi,
Following up about 'what's good,'... in this thread I focused on virtues that grant experience over time, using Good Parens as a baseline for immediate xp gratification. 
The actual value of xp is a different matter entirely!
The way I see it, the virtue of virtues lies in the capabilities they provide.
LLSM is a favorite, because it immediately allows access to any level 15 spell, and others too. Sure, there's a risk! Yet the player can choose the risk. It is a nasty risk too, which makes the virtue fairly priced.
By contrast, I like Cautious Sorcerer and always want to have it, yet it doesn't open capabilities; I see this as a supplemental virtue.
By contrast, I find Diedne Magic sub-par. It takes a long, long time for it to fulfill its potential and offer a character new capability.
Maxing out a TeFo does more than just give more of the same. It provides different kinds of spells. It provides penetration. It provides a better familiar. It makes teaching an apprentice more effective. It provides wide capabilities in almost 30% of all Hermetic Magic.
By contrast, I always want to increase characteristics because they offer broad value--yet the small benefit doesn't usually provide a new capability. Thus, given the choice between increasing Intelligence by one point or Magic Theory by two, I find the latter more attractive.
By contrast, maxing out all Hermetic casting offers diminishing returns. If my magus can solve a problem one way, being able to solve it a second and third way offers choices, but less capability. It also makes the character less interesting, because it's always fun to see how a character who only has a hammer manages to transform his problem into a nail.
My love for SFB isn't just about the 225xp I extract from it; that 225xp might be Second Sight 3, Folk Ken 2, four Craft skills at 1, Music 4, Carouse 3, Brawl 4.... These are capabilities too!
Bringing this back around to Warrior.... the 50xp it provides can be viewed as Some Weapon Ability 4. Which is a nice capability, if this is the hammer you want to give your magus. And, since Warrior lets you spend xp on weapon skills, why not be descended from a Faerie Knight, and give yourself 225xp of martial skills?
(Or better yet, work with your SG on the faerie bonus of being a Faerie Knight, so you don't need Warrior anymore. I love SFB! It also attaches a character to real medieval mythology. Being related to demons or faeries explains how a wizard is a wizard quite nicely too.)
Anyway,
Ken